Elements in qemu SGLists can cross IOMMU page boundaries. So, in commit
39c138c842 "usb: Fix usb_packet_map() in the
presence of IOMMUs", I changed usb_packet_map() to split up each SGList
element on IOMMU page boundaries and each resulting piece of qemu's memory
space separately to the iovec the usb code uses internally.
That was correct in concept, but the patch has a bug. The 'base' variable
correctly steps through the dma address of each piece, but then we call
the dma_memory_map() function on the base address of the whole SGList
element every time.
This patch fixes at least one problem using XHCI on the pseries guest
machine. It didn't affect OHCI because that doesn't use usb_packet_map().
In theory it also affects EHCI, but we haven't observed that in practice.
I think the transfers were small enough on EHCI that they never crossed an
IOMMU page boundary in practice.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
With the IOMMU infrastructure introduced before 1.2, we need to use
dma_memory_map() to obtain a qemu pointer to memory from an IO bus address.
However, dma_memory_map() alters the given length to reflect the length
over which the used DMA translation is valid - which could be either more
or less than the requested length.
usb_packet_map() does not correctly handle these cases, simply failing if
dma_memory_map() alters the requested length. If dma_memory_map()
increased the length, we just need to use the requested length for the
qemu_iovec_add(). However, if it decreased the length, it means that a
single DMA translation is not valid for the whole sglist element, and so
we need to loop, splitting it up into multiple iovec entries for each
piece with a DMA translation (in practice >2 pieces is unlikely).
This patch implements the correct behaviour
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
The USB UHCI and EHCI drivers were converted some time ago to use the
pci_dma_*() helper functions. However, this conversion was not complete
because in some places both these drivers do DMA via the usb_packet_map()
function in usb-libhw.c. That function directly used
cpu_physical_memory_map().
Now that the sglist code uses DMA wrappers properly, we can convert the
functions in usb-libhw.c, thus conpleting the conversion of UHCI and EHCI
to use the DMA wrappers.
Note that usb_packet_map() invokes dma_memory_map() with a NULL invalidate
callback function. When IOMMU support is added, this will mean that
usb_packet_map() and the corresponding usb_packet_unmap() must be called in
close proximity without dropping the qemu device lock - otherwise the guest
might invalidate IOMMU mappings while they are still in use by the device
code.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Reorganize usb source files. Create a new hw/usb/ directory and move
all usb source code to that place. Also make filenames a bit more
descriptive. Host adapters are prefixed with "hch-" now, usb device
emulations are prefixed with "dev-". Fixup paths Makefile and include
paths to make it compile. No code changes.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
